In general, the multilayer ceramic capacitor includes a plurality of laminated dielectric layers, a plurality of internal electrode layers that are disposed between the dielectric layers, and external electrodes that are disposed on both end surfaces of a stacked body composed of the dielectric layers and the internal electrode layers and are connected to the internal electrode layers. After preparing the stacked body formed by co-firing the dielectric layers and the internal electrode layers, the external electrode is formed on both end surfaces of the stacked body to prepare the multilayer ceramic capacitor.
The stacked body is prepared as follows. A plurality of sheets, which are obtained by forming a conductive paste layer that becomes an internal electrode layer on a green sheet that becomes a dielectric layer, are laminated to prepare a green stacked body, and then the green stacked body is fired to prepare the stacked body. During the firing, a ceramic powder that is a dielectric, and a metal powder of silver (Ag) or the like that is a conductive material of the internal electrode layer have sintering shrinkage behaviors different from each other. Therefore, in the stacked body obtained after the firing, a gap is frequently formed between the dielectric layers and the internal electrode layers. When the gap exists from an end surface of the stacked body to the inside of the stacked body, there is a problem that a plating solution or moisture may intrude into the inside of the stacked body through the gap during a subsequent process of forming the external electrode, particularly, during a subsequent plating process, and thus an insulating property deteriorates and reliability is lowered. In addition, there is a concern that moisture remaining in the gap may expand due to heating during mounting of the multilayer ceramic capacitor on a circuit substrate and the like, and thus the multilayer ceramic capacitor may be broken.
As a structure configured to cope with the above-described problem, such a structure is known that a semiconductor portion of the dielectric at the periphery of the ends of the internal electrodes is disposed between the internal electrode layers and the external electrode, and the internal electrode layers and the external electrode are electrically connected, but are structurally separated by a semiconductor layer (for example, refer to Patent Literature 1).